Mont. Code Ann. § 33-22-1905

A health benefit plan may not impose a surcharge or additional copayments or deductibles upon a covered person who seeks or receives health care services under 33-22-1903 or 33-22-1904 unless similar surcharges or additional copayments or deductibles are imposed for other types of health care services not described in 33-22-1903 and 33-22-1904.